1. Field of the Invention
The present invention relates to a process cartridge, an electrophotographic image forming apparatus onto which the process cartridge is detachably mountable, and an electrophotographic image forming system.
Note that the electrophotographic image forming apparatus and system include, for example, an electrophotographic copying machine, an electrophotographic printer (e.g., an LED printer, a laser beam printer, and the like), an electrophotographic facsimile apparatus, an electrophotographic wordprocessor, and the like.
On the other hand, the process cartridges include one that integrates developing means or cleaning means with charging means and an electrophotographic photosensitive member as a cartridge, which is detachably mountable to a main body of the image forming apparatus, one that integrates at least one of the developing means and the cleaning means with the charging means and the electrophotographic photosensitive member as a cartridge, which is detachably mountable to the main body of the image forming apparatus, and furthermore, one that integrates at least the charging means with the electrophotographic photosensitive member as a cartridge, which is detachably mountable to the main body of the image forming apparatus.
2. Related Background Art
Conventionally, an electrophotographic image forming apparatus and an electrophotographic image forming system, which use an electrophotographic image forming process, adopts a process cartridge system, in which an electrophotographic photosensitive member and process means for acting on the electrophotographic photosensitive member are integrated as a cartridge, which is detachably mountable on the main body of the image forming apparatus. According to this process cartridge system, the user himself or herself can maintain the apparatus without the help of a service person, and operability can be greatly improved. For this reason, the process cartridge system is prevalently used in image forming apparatuses.
On the other hand, in this process cartridge system, a demand has arisen for easy operability upon attaching/detaching the process cartridge to/from the main body of the image forming apparatus.
Furthermore, in order to allow easy mounting of the process cartridge on the image forming apparatus, when the cartridge is mounted at a predetermined position, electrical contacts are automatically connected. As an example of such arrangement, an electrical contact arrangement shown in FIG. 17 has been put into practical application. A process cartridge B shown in FIG. 17 has a plurality of electrical contacts. More specifically, the process cartridge B shown in FIG. 17 has a conductive charge contact 120, which is electrically connected to a charging roller shaft (not shown) to impress a charging voltage from the main body of the image forming apparatus to charging means (not shown), a conductive developing contact 121, which is electrically connected to a developing roller (not shown) to impress a developing voltage from the main body of the image forming apparatus to developing means (not shown), and a conductive-toner-remaining-amount detecting contact 122, which is electrically connected to an antenna rod (not shown) to detect the remaining amount of toner. All these three contacts are partially exposed from the bottom surface at one end in a longitudinal direction of the process cartridge B. The three contacts 120 to 122 are separated by distances with which they do not cause electrical leakage. The toner-remaining-amount-detecting contact 122 also serves as a process-cartridge-detecting contact for detecting whether the process cartridge B is mounted on the image forming apparatus.
Furthermore, in order to allow a simple electrical layout of circuit boards, wires, and the like on the main body of the image forming apparatus, a drum-earth contact 23a is provided to the same end portion as the three contacts in the longitudinal direction of the process cartridge.
The three contacts are formed by laying a conductive metal plate (e.g., stainless steel, phosphor bronze) having a thickness of about 0.1 mm to 0.3 mm, on the interior of the process cartridge, and the drum earth contact 23a is also formed of a conductive member and can be electrically connected to a photosensitive drum via another conductive member (not shown).
Connections between the contacts provided on the process cartridge B and the contacts provided on the image forming apparatus will be explained below. Contact members 124, 125, and 126 of the image forming apparatus are respectively biased by compression coil springs 129, and project upward from holders 127. This structure will be explained taking the charge contact member 124 as an example. The charge contact member 124 is attached inside the holder 127 to be unremovable and projectable upward. The holder 127 is fixed to an electrical circuit board attached to the main body of the image forming apparatus, and the contact member and a wire pattern are electrically connected to each other via the conductive compression coil spring 129. Before the process cartridge B is inserted into the image forming apparatus and reaches a predetermined-mount position, the contact members 124 to 126 are biased upward by the biasing forces of their compression coil springs 129. When the process cartridge B is mounted at the predetermined position, the contacts 120 to 122 of the process cartridge B make the contact members 124 to 126 retract against the biasing forces of the springs 129, thus obtaining a predetermined contact pressure. In this manner, the contacts 120 to 122 of the process cartridge B are brought into contact with the contact members, and can receive various voltages. The image forming apparatus recognizes, based on the toner-remaining-amount detecting contact 122 and the contact member 126, whether the process cartridge B has been mounted.